• 폴리머
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• 제27권3호
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• pp.201-209
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• 2003

나일론의 종류에 따른 분쇄형 탄소 섬유/나일론 복합재료의 직류 및 교류 전도도, 그리고 전자기파 차폐 효율을 조사하였다. 탄소 섬유의 함량이 약 7 vol%에서 전도도가 급격하게 증가하는 percolation 전이가 관찰되었다. 나일론 46을 기저 수지로 하였을 경우 더욱 높은 전기 전도도를 나타냈으며, 계면 결합제의 적용 여부에 따라 전도도의 차이가 발생하였다. 온도증가에 따라 전도도가 증가하는 negative temperature coefficient 현상을 나타냈으며, percolation 전후의 탄소 섬유 함량에서의 주파수에 따른 전도기구를 완화와 공진 현상으로 각각 달리 설명할 수 있었다. 회로망 분석기를 통하여 측정한 전자기파 차폐 효율은 전도도 및 탄소 섬유의 함량에 따라 증가하였으며, 높은 전도도 영역에서의 전자기파 차폐 효율은 반사에 의한 차폐가 지배적이었다.

• Bulletin of the Korean Chemical Society
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• 제15권2호
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• pp.154-161
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• 1994

Studies have been conducted to explore single electron transfer (SET) induced photocyclization reactions of N-(trimethylsilylmethylthioalkyl)phthalimides (alkyl=ethyl, n-propyl, n-butyl, n-pentyl, and n-hexyl). Photocyclizations occur in methanol in modest to high yields to produce cyclized products in which phthalimide carbonyl carbon is bonded to the carbon of side chain in place of the trimethylsilyl group. Mechanism for these photocyclizations involving intramolecular SET from sulfur in the ${\alpha}$-silylmethylthioalkyl groups to the singlet excited state phthalimide moieties followed by desilylation of the intermediate ${\alpha}$ -silylmethylthio cation radicals and cyclization by radical coupling is proposed. In contrast, photoreactions of N-(trimethylsilylmethylthioalkyl)phthalimides in acetone follow different reaction routes to produce another cyclized products in which carbon-carbon bond formation takes place between the phthalimide carbonyl carbon and the carbon ${\alpha}$ to silicon and sulfur atoms via triplet carbonyl hydrogen abstraction pathway. The normal singlet SET pathway dominates this triplet process for photoreactions of these substances in methanol while the triplet process dominates the singlet SET pathway for those in acetone. The efficient and regioselective cyclization reactions observed for photolyses in methanol represent synthetically useful processes for construction of medium and large ring heterocyclic compounds.

• Bulletin of the Korean Chemical Society
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• 제13권2호
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• pp.166-172
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• 1992

Studies have been conducted to explore single electron transfer (SET) induced photocyclization reactions of N-(trimethylsilylmethoxyalkyl)phthalimides(alkyl=E thyl, n-propyl, n-butyl, n-pentyl, and n-octyl). Photocyclizations occur in methanol in high yields to produce cyclized products in which phthalimide carbonyl carbon is bonded to the carbon of side chain in place of the trimethylsilyl group. Mechanism for these photocyclizations involving intramolecular SET from oxygen in the $\alpha-silylmethoxy$ groups to the singlet excited state phthalimide moieties followed by desilylation of the intermediate $\alpha-silylmethoxy$ cation radicals and cyclization by radical coupling are proposed. In contrast, photoreaction of N-(trimethylsilylmethoxyethyl) phthalimide in acetone follows different reaction routes to produce two cyclized products in which carbon-carbon bond formation takes place between the phthalimide carbonyl carbon and the carbon $\alpha$ to silicon and oxygen atoms via triplet carbonyl hydrogen abstraction triplet carbonyl silyl group abstraction pathways. The normal singlet SET pathway dominates these triplet processes for photoreaction of this substance in methanol. The efficient and regioselective cyclization reactions observed for photolysis in methanol represent synthetically useful processes for construction of medium and large ring heterocyclic compounds.

• Bulletin of the Korean Chemical Society
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• 제31권3호
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• pp.650-652
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• 2010

A lipase from Pseudomonas cepacia was immobilized onto single walled carbon nanotubes (SWNTs) in two different ways in each of two solvent systems (buffer and ionic liquid). The most efficient immobilization was achieved in ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, BMIM-$BF_4$). In this procedure, carbon nanotubes were first functionalized noncovalently with 1-pyrenebutyric acid N-hydroxysuccinimide ester and then subject to the coupling reaction with the lipase in ionic liquid. The resulting immobilized enzyme displayed the highest activity in the transesterification of 1-phenylethyl alcohol in the presence of vinyl acetate in toluene.

• Elastomers and Composites
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• 제41권3호
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• pp.164-171
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• 2006

실리카 또는 카본블랙으로 보강된 SBR 가황물의 응력 풀림 거동을 연구하였다. 1,2-단위체 함량이 18과 60 wt%인 두 가지 SBR을 사용하였으며 보강 시스템으로 카본블랙과 실리카에 실란 결합제가 없는 것 그리고 실리카에 실란 결합제가 있는 것 등 세 가지를 사용하였다. SBR 가황물의 응력 풀림 거동은 보강 시스템뿐만 아니라 SBR 종류에 따라서도 달라졌다. 실리카로 보강된 시료는 카본블랙으로 보강된 시료보다 잔류 변형률이 높았다. 실리카로 보강된 가황물의 잔류 변형률은 실란 커플링제를 첨가함으로써 크게 감소하였다. 카본블랙으로 보강된 가황물의 50% 최대 신장에서의 최대 하중은 실리카로 보강된 가황물의 경우보다 낮았다. 이와는 반대로 카본블랙으로 보강된 가황물의 200% 최대 신장에서의 최대 하중은 실리카로 보강된 가황물의 경우보다 높았다. 1,2-단위체 함량이 60 wt%인 시료의 최대 하중은 1,2-단위체 함량이 18 wt%인 시료의 경우보다 보강 시스템에 상관없이 높았다.

• Journal of Industrial and Engineering Chemistry
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• 제68권
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• pp.387-392
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• 2018

Various technical approaches and concepts have been proposed to develop conductive super-hydrophobic (SH) surfaces. However, most of these approaches are not usable in practical applications because of insufficient adhesion and cost issues. Additionally, durability and uniformity issues are still in need of improvement. The goal of this research is to produce a large-area conductive SH surface with improved adhesion performance and uniformity. To this end, carbon nanotubes (CNT) with a high aspect ratio and elastomeric polymer were utilized as a conductive filler and matrix, respectively, to form a coating layer. Additionally, nanoscale silica particles were utilized for stable implementation of the conductive SH surface. To improve the adhesion properties between the SH coating layer and substrate, pretreatment of the substrate was conducted by utilizing both wet and dry etching processes to create specific organic functional groups on the substrate. Following pretreatment of the surface, a zirco-aluminate coupling agent was utilized to enhance adhesion properties between the substrate and the SH coating layer. Raman spectroscopy revealed that adhesion was greatly improved by the formation of a chemical bond between the substrate and the SH coating layer at an optimal coupling agent concentration. The developed conductive SH coating attained a high electromagnetic interference (EMI) shielding effectiveness, which is advantageous in self-cleaning EMI shielding applications.

• 멤브레인
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• 제6권2호
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• pp.109-116
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• 1996

본 연구는 흡착과 막분리를 결합시킨 혼성 시스템을 폐수처리에 응용하기 위한 기초 연구로서, 페놀을 분말활성탄에 의해 흡착하고, 흡착된 페놀을 활성탄과 함께 정밀여과에 의해 분리하였다. 분말활성탄의 입자크기가 클수록 여과저항은 감소하였으며, 활성탄의 양이 적을수록 단절점(break point) 이전의 투과농도 변화율과 페놀 부하 변화율은 증가하였다. 분말활성탄의 입자크기가 작을수록 활성탄의 외표면적과 경막물질전달계수의 증가로 인해 단절점 전의 투과농도는 감소하였다.

• Rapid Communication in Photoscience
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• 제3권3호
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• pp.56-58
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• 2014

Single-walled carbon nanotubes (SWNTs) catalyzed hydrogen production from water containing various electron donors under visible light (${\lambda}$ > 420 nm). As-received SWNTs were effective for hydrogen production, yet the effect vanished when they underwent surface chemical treatments. Upon coupling with CdSe particles, however, the surface treated SWNTs were far superior to non-treated SWNTs by a factor of ~30 for hydrogen production.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 추계학술발표회초록집
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• pp.53-53
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• 2003

유도 결합 플라즈마는 비교적 간단한 방법으로 1$\times$$10^{10}$㎤ 이상의 높은 플라즈마 밀도, 저용량 결합(low capacitive coupling), 대면적 균일성을 제공하기 때문에 플라즈마 공정의 관점에서 매우 효율적이다. 따라서 유도 결합 플라즈마의 이러한 장점들은 화학적 기상 증착법으로 적용하였을 때 코팅의 특성을 향상시키는데 매우 유리할 것으로 생각된다. 특히, 좋은 특성을 가진 carbon nitride 박막을 제조하기 위해서 높은 밀도를 이용한 반응 기체의 분해와 상온에서의 증착이 필수적인데, 유도 결합 플라즈마 공정은 이런 점에서 매우 효과적이다.

• Carbon letters
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• 제10권3호
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• pp.190-197
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• 2009

Various silanes, amino silane, vinyl silane, sulfur silane (TESPD), and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB) and CIIR/hard clay/CB compounds and they are investigated with respect to the vulcanization characteristics, the processability, and the mechanical properties. Comparing hard clay and soft clay filled compounds, hard clay (Suprex) filled system shows a higher die C tear than the soft clay (GK) filled one. The other properties (Mooney, extrusion torque/pressure, torque rise ($M_H-M_L$), modulus at 300%) are close to each other. Among various silanes, the ZS treated hard clay (Suprex) compound shows the highest mechanical property following hard clay(S)/vinyl silane(V) and soft clay(GK)/vinyl silane(V) compounds. The TESPD and the ZS effectively helps a formation of a strong 3-dimensional network structure between silica and CIIR via coupling reaction due to bifunctional nature of TESPD. In addition to that, the ZS added compounds show both a better processability and mechanical properties compared to the S2 ones at low concentration due to improved compatibility between zinc soap and CIIR matrix. Only the ZS added compound shows both improved processabilities (Mooney, Extrusion torque-& pressure) and improved mechanical properties (degree of crosslinking, elongation modulus, tear, and fatigue to failure counts) on both CIIR/hard clay/CB and CIIR/soft clay/CB compounds.